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Commit877b088

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Avoid allocations in critical sections.
If a palloc in a critical section fails, it becomes a PANIC.
1 parentc7b3539 commit877b088

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4 files changed

+49
-57
lines changed

4 files changed

+49
-57
lines changed

‎src/backend/access/nbtree/nbtinsert.c

Lines changed: 29 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -1995,8 +1995,10 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
19951995
BTPageOpaquelopaque;
19961996
ItemIditemid;
19971997
IndexTupleitem;
1998-
Sizeitemsz;
1999-
IndexTuplenew_item;
1998+
IndexTupleleft_item;
1999+
Sizeleft_item_sz;
2000+
IndexTupleright_item;
2001+
Sizeright_item_sz;
20002002
Buffermetabuf;
20012003
Pagemetapg;
20022004
BTMetaPageData*metad;
@@ -2016,6 +2018,26 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
20162018
metapg=BufferGetPage(metabuf);
20172019
metad=BTPageGetMeta(metapg);
20182020

2021+
/*
2022+
* Create downlink item for left page (old root). Since this will be the
2023+
* first item in a non-leaf page, it implicitly has minus-infinity key
2024+
* value, so we need not store any actual key in it.
2025+
*/
2026+
left_item_sz=sizeof(IndexTupleData);
2027+
left_item= (IndexTuple)palloc(left_item_sz);
2028+
left_item->t_info=left_item_sz;
2029+
ItemPointerSet(&(left_item->t_tid),lbkno,P_HIKEY);
2030+
2031+
/*
2032+
* Create downlink item for right page. The key for it is obtained from
2033+
* the "high key" position in the left page.
2034+
*/
2035+
itemid=PageGetItemId(lpage,P_HIKEY);
2036+
right_item_sz=ItemIdGetLength(itemid);
2037+
item= (IndexTuple)PageGetItem(lpage,itemid);
2038+
right_item=CopyIndexTuple(item);
2039+
ItemPointerSet(&(right_item->t_tid),rbkno,P_HIKEY);
2040+
20192041
/* NO EREPORT(ERROR) from here till newroot op is logged */
20202042
START_CRIT_SECTION();
20212043

@@ -2033,16 +2055,6 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
20332055
metad->btm_fastroot=rootblknum;
20342056
metad->btm_fastlevel=rootopaque->btpo.level;
20352057

2036-
/*
2037-
* Create downlink item for left page (old root). Since this will be the
2038-
* first item in a non-leaf page, it implicitly has minus-infinity key
2039-
* value, so we need not store any actual key in it.
2040-
*/
2041-
itemsz=sizeof(IndexTupleData);
2042-
new_item= (IndexTuple)palloc(itemsz);
2043-
new_item->t_info=itemsz;
2044-
ItemPointerSet(&(new_item->t_tid),lbkno,P_HIKEY);
2045-
20462058
/*
20472059
* Insert the left page pointer into the new root page. The root page is
20482060
* the rightmost page on its level so there is no "high key" in it; the
@@ -2051,32 +2063,20 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
20512063
* Note: we *must* insert the two items in item-number order, for the
20522064
* benefit of _bt_restore_page().
20532065
*/
2054-
if (PageAddItem(rootpage, (Item)new_item,itemsz,P_HIKEY,
2066+
if (PageAddItem(rootpage, (Item)left_item,left_item_sz,P_HIKEY,
20552067
false, false)==InvalidOffsetNumber)
20562068
elog(PANIC,"failed to add leftkey to new root page"
20572069
" while splitting block %u of index \"%s\"",
20582070
BufferGetBlockNumber(lbuf),RelationGetRelationName(rel));
2059-
pfree(new_item);
2060-
2061-
/*
2062-
* Create downlink item for right page. The key for it is obtained from
2063-
* the "high key" position in the left page.
2064-
*/
2065-
itemid=PageGetItemId(lpage,P_HIKEY);
2066-
itemsz=ItemIdGetLength(itemid);
2067-
item= (IndexTuple)PageGetItem(lpage,itemid);
2068-
new_item=CopyIndexTuple(item);
2069-
ItemPointerSet(&(new_item->t_tid),rbkno,P_HIKEY);
20702071

20712072
/*
20722073
* insert the right page pointer into the new root page.
20732074
*/
2074-
if (PageAddItem(rootpage, (Item)new_item,itemsz,P_FIRSTKEY,
2075+
if (PageAddItem(rootpage, (Item)right_item,right_item_sz,P_FIRSTKEY,
20752076
false, false)==InvalidOffsetNumber)
20762077
elog(PANIC,"failed to add rightkey to new root page"
20772078
" while splitting block %u of index \"%s\"",
20782079
BufferGetBlockNumber(lbuf),RelationGetRelationName(rel));
2079-
pfree(new_item);
20802080

20812081
/* Clear the incomplete-split flag in the left child */
20822082
Assert(P_INCOMPLETE_SPLIT(lopaque));
@@ -2129,6 +2129,9 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
21292129
/* done with metapage */
21302130
_bt_relbuf(rel,metabuf);
21312131

2132+
pfree(left_item);
2133+
pfree(right_item);
2134+
21322135
returnrootbuf;
21332136
}
21342137

‎src/backend/access/spgist/spgdoinsert.c

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -122,7 +122,8 @@ cmpOffsetNumbers(const void *a, const void *b)
122122
*
123123
* NB: this is used during WAL replay, so beware of trying to make it too
124124
* smart. In particular, it shouldn't use "state" except for calling
125-
* spgFormDeadTuple().
125+
* spgFormDeadTuple(). This is also used in a critical section, so no
126+
* pallocs either!
126127
*/
127128
void
128129
spgPageIndexMultiDelete(SpGistState*state,Pagepage,
@@ -131,7 +132,7 @@ spgPageIndexMultiDelete(SpGistState *state, Page page,
131132
BlockNumberblkno,OffsetNumberoffnum)
132133
{
133134
OffsetNumberfirstItem;
134-
OffsetNumber*sortednos;
135+
OffsetNumbersortednos[MaxIndexTuplesPerPage];
135136
SpGistDeadTupletuple=NULL;
136137
inti;
137138

@@ -145,7 +146,6 @@ spgPageIndexMultiDelete(SpGistState *state, Page page,
145146
* replacement tuples.) However, we must not scribble on the caller's
146147
* array, so we have to make a copy.
147148
*/
148-
sortednos= (OffsetNumber*)palloc(sizeof(OffsetNumber)*nitems);
149149
memcpy(sortednos,itemnos,sizeof(OffsetNumber)*nitems);
150150
if (nitems>1)
151151
qsort(sortednos,nitems,sizeof(OffsetNumber),cmpOffsetNumbers);
@@ -173,8 +173,6 @@ spgPageIndexMultiDelete(SpGistState *state, Page page,
173173
elseif (tupstate==SPGIST_PLACEHOLDER)
174174
SpGistPageGetOpaque(page)->nPlaceholder++;
175175
}
176-
177-
pfree(sortednos);
178176
}
179177

180178
/*

‎src/backend/access/transam/xlog.c

Lines changed: 8 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -859,9 +859,8 @@ XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata)
859859

860860
if (rechdr==NULL)
861861
{
862-
rechdr=malloc(SizeOfXLogRecord);
863-
if (rechdr==NULL)
864-
elog(ERROR,"out of memory");
862+
staticcharrechdrbuf[SizeOfXLogRecord+MAXIMUM_ALIGNOF];
863+
rechdr= (XLogRecord*)MAXALIGN(&rechdrbuf);
865864
MemSet(rechdr,0,SizeOfXLogRecord);
866865
}
867866

@@ -3080,6 +3079,7 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
30803079
{
30813080
charpath[MAXPGPATH];
30823081
chartmppath[MAXPGPATH];
3082+
charzbuffer_raw[BLCKSZ+MAXIMUM_ALIGNOF];
30833083
char*zbuffer;
30843084
XLogSegNoinstalled_segno;
30853085
intmax_advance;
@@ -3118,16 +3118,6 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
31183118

31193119
unlink(tmppath);
31203120

3121-
/*
3122-
* Allocate a buffer full of zeros. This is done before opening the file
3123-
* so that we don't leak the file descriptor if palloc fails.
3124-
*
3125-
* Note: palloc zbuffer, instead of just using a local char array, to
3126-
* ensure it is reasonably well-aligned; this may save a few cycles
3127-
* transferring data to the kernel.
3128-
*/
3129-
zbuffer= (char*)palloc0(XLOG_BLCKSZ);
3130-
31313121
/* do not use get_sync_bit() here --- want to fsync only at end of fill */
31323122
fd=BasicOpenFile(tmppath,O_RDWR |O_CREAT |O_EXCL |PG_BINARY,
31333123
S_IRUSR |S_IWUSR);
@@ -3144,7 +3134,12 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
31443134
* fsync below) that all the indirect blocks are down on disk.Therefore,
31453135
* fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the
31463136
* log file.
3137+
*
3138+
* Note: ensure the buffer is reasonably well-aligned; this may save a few
3139+
* cycles transferring data to the kernel.
31473140
*/
3141+
zbuffer= (char*)MAXALIGN(zbuffer_raw);
3142+
memset(zbuffer,0,BLCKSZ);
31483143
for (nbytes=0;nbytes<XLogSegSize;nbytes+=XLOG_BLCKSZ)
31493144
{
31503145
errno=0;
@@ -3167,7 +3162,6 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
31673162
errmsg("could not write to file \"%s\": %m",tmppath)));
31683163
}
31693164
}
3170-
pfree(zbuffer);
31713165

31723166
if (pg_fsync(fd)!=0)
31733167
{

‎src/backend/storage/page/bufpage.c

Lines changed: 9 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@
1515
#include"postgres.h"
1616

1717
#include"access/htup_details.h"
18+
#include"access/itup.h"
1819
#include"access/xlog.h"
1920
#include"storage/checksum.h"
2021
#include"utils/memdebug.h"
@@ -433,8 +434,6 @@ PageRepairFragmentation(Page page)
433434
Offsetpd_lower= ((PageHeader)page)->pd_lower;
434435
Offsetpd_upper= ((PageHeader)page)->pd_upper;
435436
Offsetpd_special= ((PageHeader)page)->pd_special;
436-
itemIdSortitemidbase,
437-
itemidptr;
438437
ItemIdlp;
439438
intnline,
440439
nstorage,
@@ -484,10 +483,11 @@ PageRepairFragmentation(Page page)
484483
((PageHeader)page)->pd_upper=pd_special;
485484
}
486485
else
487-
{/* nstorage != 0 */
486+
{
488487
/* Need to compact the page the hard way */
489-
itemidbase= (itemIdSort)palloc(sizeof(itemIdSortData)*nstorage);
490-
itemidptr=itemidbase;
488+
itemIdSortDataitemidbase[MaxHeapTuplesPerPage];
489+
itemIdSortitemidptr=itemidbase;
490+
491491
totallen=0;
492492
for (i=0;i<nline;i++)
493493
{
@@ -532,8 +532,6 @@ PageRepairFragmentation(Page page)
532532
}
533533

534534
((PageHeader)page)->pd_upper=upper;
535-
536-
pfree(itemidbase);
537535
}
538536

539537
/* Set hint bit for PageAddItem */
@@ -782,8 +780,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
782780
Offsetpd_lower=phdr->pd_lower;
783781
Offsetpd_upper=phdr->pd_upper;
784782
Offsetpd_special=phdr->pd_special;
785-
itemIdSortitemidbase,
786-
itemidptr;
783+
itemIdSortDataitemidbase[MaxIndexTuplesPerPage];
784+
itemIdSortitemidptr;
787785
ItemIdlp;
788786
intnline,
789787
nused;
@@ -795,6 +793,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
795793
intnextitm;
796794
OffsetNumberoffnum;
797795

796+
Assert(nitems<MaxIndexTuplesPerPage);
797+
798798
/*
799799
* If there aren't very many items to delete, then retail
800800
* PageIndexTupleDelete is the best way. Delete the items in reverse
@@ -829,7 +829,6 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
829829
* still validity-checking.
830830
*/
831831
nline=PageGetMaxOffsetNumber(page);
832-
itemidbase= (itemIdSort)palloc(sizeof(itemIdSortData)*nline);
833832
itemidptr=itemidbase;
834833
totallen=0;
835834
nused=0;
@@ -895,8 +894,6 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
895894

896895
phdr->pd_lower=SizeOfPageHeaderData+nused*sizeof(ItemIdData);
897896
phdr->pd_upper=upper;
898-
899-
pfree(itemidbase);
900897
}
901898

902899

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